VHZ is a phosphatase that shares about 28% amino acid sequence identity with human PRL-PTPs. VHZ was previously reported to be expressed in many tissues and located in the cytosol and in nucleoli (Alonso et al., 2004a).
However, the role of VHZ was largely unknown; despite its conservation through evolution with orthologues in frogs, fish, fly, and the Archaea. VHZ, as well as VHR, belongs to a separate subgroup of VH1-like PTPs (Alonso et al, 2004b). VHR has been reported to have a function in regulating cell cycle progression (Rahmouni et al., 2006).
In the Western world and the developed countries of Asia, breast carcinoma is the second leading cause of cancer-related death in women (Polyak, 2001). Breast cancer tops the cancer list for women in Singapore, with 700-800 new cases being diagnosed each year (Singapore Cancer Registry Report, 2000). In the USA, 180,000 women are diagnosed annually with new cases of breast cancer (Polyak, 2001). Despite better diagnosis and routine screening around a quarter of the cases will die from their disease.
Accordingly, there is a need for improved breast cancer detection and therapy.